<body>Dear Rodolphe,<br /><br />strictly speaking cluster analysis (as a construct to get a univariate test instead of a mass-univariate one) only tells you that there IS a significant cluster. The exact shape and temporal evolution of this cluster is not part of what's tested - as least as far as I understand this issue. That is a data point can surpass your cluster inclusion threshold by chance - a portion of alpha data points will actually do this. In addition, these point can be accidentally close to other clustermembers. Hence, it will be included in a cluster. So 'true' cluster membership of a certain electrode/timepoint/frequency is not statistically 'guaranteed'. Additional tests would be necessary.<br />Then one thing that this argument does not account for is that 'accidentally neighbouring a cluster' is not so likely because of the smoothness of MEEG data - but I do not know at the moment how you could exploit this.<br /><br />Michael<br /><span style="font-size: 9pt;"><span style="font-family: verdana,geneva;"><span style="background-color: transparent;"><span style="color: #000000;"><span style="color: #000000;"></span></span></span></span></span><span style="font-size: 9pt;"><span style="font-family: verdana,geneva;"><span style="background-color: transparent;"><span style="color: #000000;"><span style="color: #000000;"><br /></span></span></span></span></span><span style="font-size: 9pt;"><span style="font-family: verdana,geneva;"><span style="background-color: transparent;"><span style="color: #000000;"><span style="color: #000000;">
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<b>Von:</b> Rodolphe <batrod@GMAIL.COM><br /><b>Gesendet:</b> Oct 20, 2010 12:49:06 AM<br /><b>An:</b> FIELDTRIP@NIC.SURFNET.NL<br /><b>Betreff:</b> [FIELDTRIP] Cluster change over time<br /><br />Dear Fieldtrip users,
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<div>I used the Monte-Carlo method with cluster correction to compare two conditions within the same group of subjects.</div>
<div>I didnt average over time, thus the clusterplot showed several topographic plot of the cluster that was found to be significant.</div>
<div>I can see that this cluster evolves over time (number and place of significant electrodes highlighted). My question is, considering the statistical method using for this analysis, can i say that this change over time is significant or does it require further analysis like ANOVAS in concerned electrodes?</div>
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<div>Thanks a lot, </div>
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<div>Rodolphe N., Ph.D.</div>
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